In surprising new research, scientists have found both humans and animals choose what to eat based on the caloric content of food, regardless of taste.
Ivan de Araujo, a neuroscientist at the Icahn School of Medicine at Mount Sinai, has shown calories can trump palatability: Their work has demonstrated mice prefer consuming bitter solutions paired with a sugar infusion rather than a calorie-free sweet solution.
De Araujo and his group have been working for years to work out how the contents of the gut produce pleasure in the brain. They have found sugar in the digestive tract can activate the brain’s reward centres. Even in animals bred without the ability to taste sweetness, sugary snacks still trigger this.
The vagus nerve, a bundle of fibers that connects the brain stem to the intestines and other major organs in the body, is the conduit of these gut-borne pleasure-related signals to the brain.
This is the mechanism that explains why the presence of calories or nutrients in the gut changes our behaviour. We still don’t understand the detail of how this works, but one thing is clear – our gut knows whether or not we have eaten artificial sweetener rather than sugar or a ‘low fat’ version of something. It can tell the calorific county of our food.
Which goes a long way to explaining why ‘diet food’ isn’t satisfying. Every cell in our body recognises what we put into it for what it is.